Back anatomy

Erector spinae

Long intrinsic back muscle columns supporting upright posture

Multifidus

Overlapping deep back muscle bundles linking nearby vertebrae

Splenius capitis

Posterior neck muscle turning the head toward its own side

Bones

Atlas (C1)

Ring-shaped first neck vertebra supporting the skull

Axis (C2)

Second neck vertebra providing the dens for head rotation

Typical cervical vertebra

Usual neck-vertebra pattern, represented by C3–C6

Typical lumbar vertebra

Large lower-back vertebra adapted for substantial loading

Typical thoracic vertebra

Rib-bearing vertebra, best illustrated in the middle thoracic region

Nerves

Cauda equina

Descending nerve roots below the end of the spinal cord

Dermatomes

Overlapping skin regions linked to spinal sensory roots

Dorsal column-medial lemniscus pathway

Ascending pathway for precise touch and body-position awareness

Dorsal root ganglion

Cluster of primary sensory neuron cell bodies on a spinal root

Lateral corticospinal tract

Descending cortical pathway important for skilled limb movement

Spinal nerve

Short nerve trunk joining sensory and motor root fibers

Spinocerebellar tracts

Pathways informing the cerebellum about limb position and spinal activity

Spinothalamic tract

Ascending anterolateral pathway for pain, temperature and coarse touch